Electronic engine controls comprise electronic circuitry, typically microprocessor based, that processes various inputs to provide the desired engine control functions. In one electronic engine control, a momentary switch input is required in order to allow engine speed to be changed. An engine-powered vehicle that has a PTO (power take-off) for allowing equipment other than the vehicle itself to be operated by the engine, requires an associated control for controlling engine operation, engine speed for example, when the PTO is in use. One type of control needs a momentary switch closure as one input for enabling a desired speed change to be performed. Heretofore, it was necessary to execute two switch operations in order to accomplish the momentary switch function and provide the desired speed change. The present invention is distinguished from the prior two switch activations by enabling single switch operation to perform the momentary switch function and provide the desired speed change.
The present invention relates to a new and unique electronic circuit for performing a momentary switch function that is suitable for accomplishing the aforementioned purpose. The invention provides: improved cost-effectiveness; greater operating convenience; and it eliminates a separate toggle switch that was required in a prior control in order to activate the PTO enabler. The invention enables an electronically controlled engine to operate equipment from the PTO in a manner similar to that previously used with mechanically controlled engines where a solenoid is linked to the pump rack of a diesel engine and controlled by a single switch.
The invention is further characterized by a unique organization and arrangement of standard electronic circuit components, and in a preferred embodiment these are four resistors, two transistors, a diode, and two capacitors. Four connections to external circuits are provided.
The closest prior art known to the inventors is a capacitor-coupled drive for switching transistors, an illustration of which appears at Page 961 of "Modern Electronic Circuits Reference Manual" by McGraw-Hill. The illustrated circuit is comparable in function to that of the present invention, but the circuit of the present invention requires fewer components, is less costly, and the prior circuit is not directly suited for the instant engine single switch PTO enabler application.
While the present invention relates in one respect to electronic engine controls where a momentary switch input is required, the electronic circuit embodied therein possesses utility for other applications, which may or may not necessarily be engine or vehicle related. One such other application is in a vehicle speed control system where the circuit can replace two switch actuation by single switch actuation.
The foregoing, along with further features, advantages, and benefits of the invention, will be seen in the ensuing description and claims, which are accompanied by a drawing. The drawing discloses a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.